Sir Mix a Lot
I like hot temps and it’s no lie
When the Celsius is above 60 degrees, oh my –
The waters flowing the bugs, ain’t growing
Hang on…why’s my skin glowin’? And that blista’ forming’?
Ever heard the phrase – “Like wearing a low cut scold” – Growing up in the eighties, this was banded about a fair bit as the hotter the water the better the wash according to some, and given that the current guidance (HSG274 part 2) for Legionella prevention requires Calorifiers and water heaters to achieve 60°C as a minimum (HSG274 part 2), is it easy to see (or feel) how accidents can happen.
The evidence for the occurrence of Legionella in water systems varies between different reports. The most representative information is summarised in a HSE ACoP document (Ref 4), which states:
· Legionella bacteria will die at temperatures above 60ºC.
· Legionella bacteria proliferate between 20ºC and 45ºC. · Legionella bacteria will not multiply at temperatures below 20ºC but will remain as a potential threat in the system.
The elderly and young kids are especially at risk from scalds and burns as they typically have thinner skin and whilst par boiling your spuds for you Sunday lunch is acceptable, medical research has suggested that ideal temperature for a soak or splash is between 32 and 40°C and whilst we now have calculators in our pockets, it’s unlikely a thermometer is part of your everyday pocket items*. There is often a legal requirement for TMV’s to be fitted, especially in Health care and educational settings. -For more info see Building Regs part G and, HTM-04-01
The NHS Estates Health Guidance Note, refers to maximum hot water and surface temperatures for safe use. These are recommended for all healthcare premises and those premises registered under the Registered Homes Act 1984 (Ref 3) but are applicable for other types of occupied building.
- 44ºC For an unassisted bath fill
- 46ºC For an assisted bath fill (**)
- 41ºC For shower applications
- 41ºC For washbasin applications
- 38ºC For bidet applications
So, what to do?
Well for the most part the senses kick in, both common and touch. Common sense suggests that if the water is steaming and radiating some heat, it might need some cold added. Equally a cursory dip of the elbow might be enough to suggest the water is a little on the warm side whilst you’re at home, although in a professional setting it is nearly impossible to get a calibration certificate for an appendage and it’s not always practical to have someone on standby to adjust the temperature, if only there was an automated solution……
Thermal Mixing Valve – The hero you never knew existed In humanities ever growing ambition of progress and automation, minds far greater than this author, created blending valves. These little inline devices use a thermostatic element to control the flow of water so that a preset temperature is achieved. Also available in as a tap/outlet, the units are a fit and almost forget type, although it is recommended that the inbuilt safety is checked six monthly, and the units are stripped and serviced annually
Essentially, with the temperatures required to kill off Legionella bacteria, scalding is a very real risk and whilst Thermal mixing valves are a fantastic tool to assist in reducing the risk, they do require correct installation and servicing., so with that in mind, we’ll let Josha Ibiyinka, have the final word.
“The tool is only as effective as the skilfulness of the hands that wield it”.
*Unless you’ve got a fancy smart phone with Thermal imaging camera – Yes, we see you ‘Cat’ and coincidentally named, ‘Doogee’ brand phones.